Unprecedented flooding covered hundreds of city blocks in Cedar Rapids as officials urged residents to limit their water use to drinking, according to the municipality's website.

In the state capital Des Moines, population 200,000, public works crews and Iowa National Guard soldiers raced to build a berm after a levee breached in the early hours of Saturday.

The University of Iowa, based in Iowa City, cancelled classes until June 22 as the flood threatened its dorms, research facilities, library and art museum. The university urged employees to work from home if possible or consider volunteering in the emergency relief efforts.

"This has been a very trying week for our state," Iowa Governor Chet Culver said in a statement. "Responding to a crisis like this takes the cooperation of everyone, from the federal government down to the local communities."

Extreme weather has left at least 15 dead and thousands homeless in the state in recent days, said Bret Voorhees, spokesman for the Iowa Homeland Security and Emergency Management.

Five others were killed in other parts of the Midwestern United States.

Two people were killed by floodwaters in Indiana and two delivery people drowned Sunday when their car fell off a washed out road into a flooded creek, the National Weather Service said.

Another person was killed Wednesday when a tornado ripped through the town of Chapman, Kansas.

The disaster began when a major tornado struck on May 25. It was followed by heavy rains, with more thunderstorms expected this weekend, and on Wednesday another twister touched ground in western Iowa, killing four boy scouts.

Serious flooding has hit the entire region, including parts of South Dakota, Minnesota, Wisconsin, Nebraska, Illinois, Indiana, Kansas, Oklahoma and Arkansas and was expected to continue through next week.

"We're trapped with nowhere to go," said Gloria Hines, who lives about a dozen blocks from where the river spilled over in Cedar Rapids.

The floodwaters had not reached her home yet, but the street was made impassable by water gushing out of storm drains. A few small fish spilled out of the contaminated sewage ways.

Torrential rains Thursday left downriver towns preparing for the worst and the National Guard called in to help an army of volunteers with sandbagging and rescue efforts.

"Our predictions of a 100-year flood, or greater, are really coming to pass," said Iowa City Mayor Regenia Bailey.

A boat ride through Cedar Rapid's water-logged downtown saw every branch of government crippled by the floods.

The library, the federal building and city hall were all filled with water, which rippled through basements and pulled files and furniture out through the windows.

Inmates in the county jail were evacuated along with their mattresses.

On one building, clutching the cats that nearly cost them their lives, perched Charles Schmitt, 19, and girlfriend Kayla Lambreacht.

They had fled their nearby home when the basement filled with water. But when they stopped to take a picture one of the cats jumped into the river, prompting Schmitt to go in after it, and his girlfriend to follow.

Clutching two storage bins that Lambreacht tossed into the water, they floated for 45 minutes before they found a building to climb into.

"We kept calling 911 but the phone went out," Schmitt said. "We were up there for two hours."

Citizens of Iowa: That's what you get for starting the political ball rolling for Barack O'Bama. Just in case you thought that George Bush and his maniacal bunch of technocrats weren't able to harness the weather for devious, destructive means. Take that !!!